The invention relates to a pulse generator for producing pulses which are synchronously associated with the movement of a mechanical element.
For the control of machines, in particular machines having rotating parts, electronic auxiliary devices are increasingly used, which require pulses for the synchronisation of the control orders or measurements given by them with the movement of the machine which are associated synchronously with this movement, for example rotational movement. For example, most auxiliary devices, in particular digital control systems, work incrementally, i.e. they require in each case a synchronous pulse to maintain the synchronisation between the machine and the control system.
Particular requirements are made of pulse generators of this type in motor vehicle design, since in this case the pulse generator preferably works in connection with the flywheel gearing, which is subject to a high degree of vibration and is located in the region of the clutch housing, in which very high temperatures can be expected. Moreover, if the pulse generator works in conjunction with an auxiliary device for the control of the injection and/or ignition of the internal combustion engine of the motor vehicle, it must possess a very low lower rotational speed limit, so that even during the starting of the internal combustion engine the generation of the pulses necessary for synchronisation and control is guaranteed.
The inductive pulse generators used hitherto for engine diagnosis, which are also termed "inductive generators" do not provide trouble free working at low rotational speeds and the use of pulse generators with field plates fails for reasons of temperature. Moreover, in each case two such pulse generators would have to be used of which one produces the actual pulses required for the control system itself while the other in each case supplies the synchronous pulse with which the synchronisation between the engine and the auxiliary device is maintained. In the latter case, the synchronous pulse in addition to the pulses required for control in the case of rotating engines is obtained by an additional angle marking in the double track method, such as is described for example in German Pat. No. 2,010,999, in which the synchronisation pulses are termed "auxiliary pulses".